Some updates in addition to sunils module_loader

Additionally to freedombox/Plinth/pull/14 this includes the following changes:
- introduced tor-actions for status/start/stop to display whether tor is running on the tor app page. The enabling/disabling functionality is already implemented in another branch that requires bootstrap3 though.
- spinning wheel (spin.js), use it when something takes longer to load, i.e. because of enabling/disabling or installing something. Please have a look whether I updated the package requirements (we now need `libjs-spin.js`) correctly.
- refactored firstboot module to make more use of django; users are now automatically logged in after they create an account.

This does not address/fix any of the issues @jvalleroy mentioned today at Sunils initial pull request.